woocommerce/includes/updates/woocommerce-update-2.4.php

<?php
/**
 * Update WC to 2.4.0
 *
 * @author 		WooThemes
 * @category 	Admin
 * @package 	WooCommerce/Admin/Updates
 * @version     2.4.0
 */

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

global $wpdb;

// Maintain the old coupon logic for upgrades
update_option( 'woocommerce_calc_discounts_sequentially', 'yes' );

/**
 * Update the old user API keys to the new Apps keys
 */
$api_users = $wpdb->get_results( "SELECT user_id FROM $wpdb->usermeta WHERE meta_key = 'woocommerce_api_consumer_key'" );
$apps_keys = array();

// Get user data
foreach ( $api_users as $_user ) {
	$user = get_userdata( $_user->user_id );
	$apps_keys[] = array(
		'user_id'         => $user->ID,
		'permission'      => $user->woocommerce_api_key_permissions,
		'consumer_key'    => $user->woocommerce_api_consumer_key,
		'consumer_secret' => $user->woocommerce_api_consumer_secret
	);
}

if ( ! empty( $apps_keys ) ) {
	// Create new apps
	foreach ( $apps_keys as $app ) {
		$wpdb->insert(
			$wpdb->prefix . 'woocommerce_api_keys',
			$app,
			array(
				'%d',
				'%s',
				'%s',
				'%s'
			)
		);
	}

	// Delete old user keys from usermeta
	foreach ( $api_users as $_user ) {
		$user_id = intval( $_user->user_id );
		delete_user_meta( $user_id, 'woocommerce_api_consumer_key' );
		delete_user_meta( $user_id, 'woocommerce_api_consumer_secret' );
		delete_user_meta( $user_id, 'woocommerce_api_key_permissions' );
	}
}

// Update fully refunded orders to ensure they have a refund line item so reports add up
$refunded_orders = get_posts( array(
	'posts_per_page' => -1,
	'post_type'      => 'shop_order',
	'post_status'    => array( 'wc-refunded' )
) );

foreach ( $refunded_orders as $refunded_order ) {
	$order_total    = get_post_meta( $refunded_order->ID, '_order_total', true );
	$refunded_total = $wpdb->get_var( $wpdb->prepare( "
		SELECT SUM( postmeta.meta_value )
		FROM $wpdb->postmeta AS postmeta
		INNER JOIN $wpdb->posts AS posts ON ( posts.post_type = 'shop_order_refund' AND posts.post_parent = %d )
		WHERE postmeta.meta_key = '_refund_amount'
		AND postmeta.post_id = posts.ID
	", $refunded_order->ID ) );

	if ( $order_total > $refunded_total ) {
		$refund = wc_create_refund( array(
			'amount'     => $order_total - $refunded_total,
			'reason'     => __( 'Order Fully Refunded', 'woocommerce' ),
			'order_id'   => $refunded_order->ID,
			'line_items' => array(),
			'date'       => $refunded_order->post_modified
		) );
	}
}

wc_delete_shop_order_transients();